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<p><em>IfcOwnerHistory</em> defines all history and identification related information. In order to provide fast access it is directly attached to all independent objects, relationships and properties.</p>

<p><em>IfcOwnerHistory</em> is used to identify the creating and owning application and user for the associated object, as well as capture the last modifying application and user.</p>

<blockquote class="history">
HISTORY&nbsp; New entity in IFC1.0. 
</blockquote>
<blockquote class="change-ifc2x4">IFC4 CHANGE&nbsp; ChangeAction is now optional and a related WHERE rule enforces conditions when it is asserted.
</blockquote>

<p class="spec-head">Informal Propositions:</p>
<ol>
<li>If LastModifiedDate is defined but ChangeAction is not asserted, then the state of ChangeAction is assumed to be UNDEFINED.</li>	  
<li>If both LastModifiedDate and ChangeAction are asserted, then the state of ChangeAction applies to the value asserted in LastModifiedDate.</li>

</ol>

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